If you do not have an ophthalmologist, or if you are away from home, find a teaching hospital that has a training program in ophthalmology, go to their emergency room, and ask to see the eye resident on call. This chapter describes several examples of each type of eye problem.
During transcription, enzymes called RNA polymerases build RNA molecules that are complementary to a portion of one strand of the DNA double helix (Figure 3). Figure 3: RNA polymerase at work. RNA polymerase (green) synthesizes a strand of RNA that is complementary to the DNA template strand below it.
RNA and Protein Synthesis. During transcription, the enzyme RNA polymerase synthesizes a strand of messenger RNA (mRNA) using one strand of the gene as a template.mRNA is synthesized using nucleotides that contain the bases A, C, G, and U (instead of T), which pair with the complementary bases of the DNA template strand.he starting point for transcription, where RNA polymerase unwinds the DNA and begins to make a complementary mRNA copy, is the promoter site; the region of DNA that is the endpoint of transcription is the terminator site; mRNA is synthesized in the 5â to 3â direction.